Park was a sophomore at Hanyang University (Seoul) in 1994 when he was signed by the Los Angeles Dodgers as an amateur free agent. A fastball pitcher, he enjoyed success with the team, playing at the pitcher-friendly Dodger Stadium. He had his best season with the Dodgers in 2000, when he went 18-10 with a 3.27 ERA and 217 strikeouts. Following a 15-11 season with the Dodgers in 2001, Park became free agent. He had made the All-Star team for the only time of his career that year.

In spite of his overall success for the Dodgers, he is best remembered for some of the times things did not go that well. On April 23, 1999, he surrendered two grand slams to Fernando Tatis in the same inning. Tatis is the only player ever to have accomplished the feat of hitting two grand slams in the same inning; that they came against the same pitcher makes it even more improbable. Park also gave up Barry Bonds' record-breaking 71st home run in 2001. Later that game, Park gave up the 72nd as well. Park remains the only pitcher ever to give up a player's 71st or 72nd home run in a season. His teammate Dennis Springer gave up the 73rd, two days later.

When with the Dodgers, Park was the instigator of a celebrated brawl with Anaheim Angels pitcher Tim Belcher. On June 5, 1999, Park triggered an altercation after Belcher forcefully tagged him out on a sacrifice bunt up the first base line. Park shoved him with both hands, then forearmed him in the face and giving him a side kick - leaving Belcher with a spike wound on his left thigh and a bruised left forearm.[1] The reason was later discovered during a Korean show that Tim Belcher had responded with racial remarks after Park complained of the forceful tag.

He was signed by the Texas Rangers in December 2001 to a five-year, $65 million contract, which was at the time one of the highest contracts ever offered to a pitcher. However, during his time with the Rangers, Park was hampered by injuries and a home stadium that notoriously favors hitters - Ameriquest Field in Arlington. In his first season with the Rangers in 2002, Park only went 9-8 in 25 starts, with a 5.75 ERA. The following season, 2003, he only started seven times due to injuries, going 1-3 with a 7.58 ERA.

Park proved to be largely unpopular with the local crowds and Dallas-area media (referred to by some media members as "Heave Ho Park" and "Oh No Park"), who considered the underperforming pitcher and his large contract to be a waste of money that hampered the team. However, they did not necessarily consider Park to be a player who could no longer succeed anywhere, but rather a player who did not fit the Rangers' organization, which traditionally focused on offense and power pitchers. Under this theory, it was Park's pitching style, which tended to induce fly balls (which at hitter-friendly Ameriquest often end up as home runs), which led to his troubles with the Rangers - and which was less of a problem when he pitched for the Dodgers, with their pitcher-friendly home park. This theory appears to be supported by evidence: From 2002 to 2004, Park had a 6.75 ERA at home, much higher than his 4.92 ERA on the road.

On June 4, 2005, Park became the first South Korean to ever reach 100 career wins in the majors. He was 26 days short of his 32nd birthday when he reached the milestone.

On July 29, 2005, Chan-Ho Park was traded by the Rangers to the San Diego Padres in exchange for Phil Nevin. He was shelled in his first outing as a Padre, giving up 7 runs and 5 earned runs in 4.1 innings with 8 hits and 3 walks. However, Park had a successful home debut as a Padre, including striking out a season-high eight in 5 2/3 innings of work. Padres fans hoped that Park could repeat his success with the Dodgers playing in pitcher-friendly PETCO Park.

In the 2006 World Baseball Classic, Park pitched extremely well, earning 3 saves. The WBC rules for pitching forced him to be excluded from Korea's final game against Japan. With his strong performance (no runs allowed in 10 innings pitched), he was selected to the All-WBC team.

He got his first taste of postseason baseball as a member of the Padres in 2006, pitching two innings of relief against the St. Louis Cardinals in Game 1 of the NLDS, giving up no runs in a 5-1 loss. That season, he had gone 7-7, 4.81 in 24 games (21 starts) with the Padres. His season had been interrupted when he was placed on the 15-day disabled list on July 31st because of intestinal bleeding that required a blood transfusion. He returned and pitched in two games before the bleeding recurred. The mysterious condition was finally diagnosed as a Meckel's diverticulum in his small intestine, which was surgically removed on August 23rd. [2]

Park signed a one-year, $600,000 deal with the New York Mets in February 2007. He only pitched one game for the 2007 Mets, allowing 7 runs in 4 IP. He then went to the AAA New Orleans Zephyrs, where he was 4-4 with a 5.57 ERA. New York let him go. While several South Koreans had moved from Organized Baseball to the Korea Baseball Organization in 2007, KBO managers were skeptical of Park coming over to their league even though Park remained a highly popular player in his native South Korea, where many people follow games whenever Park pitches. He wound up signing a minor league deal with the Houston Astros.

In the 2007 Asian Championship, Park threw three scoreless innings, allowing four hits, striking out four and walking one as South Korea finished second.

On April 4, 2008 the Dodgers purchased Park's contract from the AAA Las Vegas 51s. The team had promised Park an early-season call-up after he surprised them with an outstanding 2008 spring training performance. He went 4-4, 3.40 as a reliever with the team, making 5 starts and picking up 2 saves. In 2009, he signed with the Philadelphia Phillies as a free agent and spent the year as a swingman, making 7 starts among his 45 appearances. He pitched 83 1/3 innings with a record of 3-3 and played in the World Series for the only time of his career, making four relief appearances with no runs allowed as the Phillied bowed out to the New York Yankees in 6 games. The Yankees must have liked what they saw, as they signed him as a free agent for 2010. His stay in pinstripes started on the wrong foot, though, as on Opening Day against the Boston Red Sox on April 4th, he entered the game in the bottom of the 7th with a 7-5 lead, but gave up a game-tying two-run homer to Dustin Pedroia and allowed Kevin Youkilis to score the winning run on a wild pitch followed by a passed ball. He then picked up a win with three scoreless innings of releief in his next outing, and went on the disabled list a few days later. He returned in mid-May only to give up at least a run in 5 of his next 6 outings. He was placed on waivers in early August, sporting a 2-1 record but a 5.60 ERA in 27 games. He was picked up by the Pittsburgh Pirates and did a lot better for them, going 2-2, 3.49 in 26 games, with 23 strikeouts against only 7 walks in 28 1/3 innings. These would turn out to be his final appearances in the big leagues, his last game coming on October 1st when he picked up a win against the Florida Marlins with 3 scoreless innings of relief. That win was historic, as it gave him 124 for his career in the big leagues, one more than former teammate Hideo Nomo for the most by an Asian-born pitcher.

Park signed with the Orix Buffaloes for 2011. He debuted on April 15, allowing three runs in 6 2/3 IP in a loss to the Rakuten Golden Eagles and Masahiro Tanaka. Injuries limited him to only 7 games that season. In 2012, he moved back to his native South Korea, pitching for the Hanwha Eagles, where he was 5-10 with a 5.06 ERA but attracted big crowds as one of the biggest names in the history of Korean baseball. On November 29, 2012, he announced his retirement as a player at age 39.